Field of the Invention
The present invention relates to a shock absorber for a railway vehicle, and more particularly, to a shock absorber for a railway vehicle, in which an eccentric disk is disposed on a rear surface of a valve disk to set a supporting force for an initial opening position of the valve disk to a relatively low value and continuously open the valve disk from the initial opening position thereof during strokes, thereby controlling a damping force in a low speed section and realizing a soft damping force.
Description of the Related Art
Generally, a shock absorber for a railway vehicle, which absorbs a shock, is used in a connection mechanism between trucks or carriages of the railway vehicle.
The shock absorber for the railway vehicle includes a cylinder filled with a working fluid and having one end connected to the railway vehicle, a piston valve partitioning the interior of the cylinder into a compression chamber and a rebound chamber and generating a damping force, and a piston rod performing compression and rebound strokes in a state of being connected to the piston valve.
The piston valve includes a body partitioning the interior of the cylinder into the compression chamber and the rebound chamber and having a main passage formed therein, and valve disks connected to upper and lower surfaces of the body in multiple layers and opening/closing the main passage.
That is, an existing piston valve has a structure in which a fluid moving through a main passage during compression and rebound strokes generates a damping force while pushing and opening a valve disk and moving toward a compression chamber or a rebound chamber.
However, in the existing piston valve, a fluid may be discontinuously discharged because an initial opening position of the valve disk is not specified during compression and rebound strokes. Thus, a discontinuous blow-off phenomenon may occur when the valve disk is opened. In addition, it is difficult to realize damping force characteristics in a low speed section.
As one of prior art documents related to the present invention, Korean Patent Application Publication No. 10-2011-0089078 (published on Aug. 4, 2011) discloses a shock absorber.